Resist pattern-improving material and a method for preparing a resist pattern by using the same

ABSTRACT

The present invention provided an improvement to reduce an edge roughness during forming a small and fine pattern. Such and objective is to accomplish that after patterning a resist film, a coating film is formed on the resist film, so as to intermix the resist film material with the coating film material at the interface therebetween to reduce the edge roughness. There is provided a resist pattern-improving material, comprising: (a) a water-soluble or alkali-soluble composition, comprising: (i) a resin, and (ii) a crosslinking agent. Alternatively, The resist pattern-improving material, comprising (a) a water-soluble or alkali-soluble composition, comprising: (i) a resin, and (ii) a nonionic surfactant. According to the present invention, a pattern is prepared in the step, comprising: (a) forming a resist pattern; and (b) coating the resist pattern-improving material on the surface of the resist pattern. According to the present invention, the resist pattern-improving material is mixed with the resist pattern at the interface therebetween. The resist pattern may be formed by irradiating a ArF excimar laser light or a laser light having a wavelength shorter than that of the ArF excimar laser light. The pattern of the resist pattern-improving material includes a base resin which does not substantially transmit the ArF excimar laser light.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2002-59429, filed on Mar. 5,2002, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a resist pattern-improving material anda method for preparing a pattern by using the same. The presentinvention, in particular, relates to an improvement for forming acoating layer on the surface of the resist pattern by photo irradiation,and intermixing the coating layer with the surface of the resistpattern, and thereby reducing an edge roughness of the pattern. Such apattern is used in semiconductor devices, magnetic sensors, variousfunctional parts, and so on.

RELATED ART

Photo irradiation techniques are generally efficient for massproduction. In order to continue to improve the efficiency of massproductivity, there has been a demand to use the photo irradiationtechniques in processing for preparing smaller and finer products.Therefore, studies have been conducted not only for selecting a farultraviolet ray having a shorter wavelength than ever as an irradiationlight, but also for improving mask patterns, shapes of the light source,and so on. There is a demand to develop an improvement that is easilycarried out by a user and that makes it possible to continue to applysuch photo irradiation techniques for precisely drawing a finer patternthan ever.

When irradiating by using a KrF (krypton fluoride) excimer laser, whichis generally used in the latest manufacturing process for semiconductordevices, the minimum resolution pattern size of 130 nm is about to beaccomplished, and if it is combined with a super resolution technology,a minimum resolution pattern size of less than 130 nm is possible. Inthe next generation of the photo irradiation techniques in the massproduction, the means of the photo irradiation is considered to selectan ArF (argon fluoride) excimer laser having a shorter wavelength thanever. When using the ArF (argon fluoride) excimer laser, it may bepossible to realize making a pattern in the level of 70 to 80 nm.However, when using a far ultraviolet ray having a shorter wavelengththan ever as an irradiating light, edge roughness is unavoidable: thatis, the smaller or finer the resist pattern is designed, the more theedge of the resist pattern is waved, although the edge is designed to beformed in a line shape. In other words, when resist pattern is drawn byirradiation of a far ultraviolet ray, a small and fine resist patternmay be expected, and the pattern has a line shape with a very littlewidth. However, as the whole of the device size is reduced and the widthof the pattern is narrowed, the edge roughness is relatively increasedcompared with the total of the width of the pattern. The current devicesused in the type of the latest generation on the average have an edgeroughness in the amount of ±5%, which is said to be a conspicuous level.It is necessary or essential to consider and create a measure to reducethe amount of the edge roughness. Otherwise, short circuit ordisconnection of the pattern may be generated in the next step of thesurface preparation step. As a result, the edge roughness willsignificantly affect the yield of the product. With reference to FIG. 1,this problem is explained more in detail. See FIG. 1.

FIG. 1 shows plan views of a pattern in the middle of preparing asemiconductor device, which illustrate the objectives in theconventional process. FIG. 1 (a) shows a plan view of a pattern to bedrawn in accordance with the design, and FIG. 1( b) shows a plan view ofan actual drawn pattern, which has an edge roughness as shown.

In the conventional way, the slashed portions shown in the figures arewhere a conductive film is formed. At the previous step, not shown inthe figures, the conductive film is coated on the whole of the surfacethereof. Then, a resist film is formed and patterned by means aphotolithographic technique, which is well known in the art. Since theedge roughness is generated in this process as shown, the resist patternresults in waving, which should be a line shape. Then, such a resistpattern is used as a mask. However, such a resist pattern accompaniedwith the edge roughness is not appropriate for precisely etching theconductive film and patterning by remaining the portion of the slashedportions as shown. The etched pattern of the conductive film issignificantly waved as shown in FIG. 1( b). In the worst case,disconnection or short circuit will occur in the pattern. Recently, theuse of copper wiring has become widespread, especially in the latestfine logic devices. However, if a pattern is formed by being transferredby the resist pattern having the edge roughness, it will be difficult tocover a copper diffusion prevention film of such a copper wiring,resulting in significantly affecting the following steps after thelithography step or resulting in loss of reliability of the device.

Improvement of several resist materials has led to reduction in the edgeroughness, and up to now, the issue of the edge roughness has not beenraised as an industrial problem. However, the resist pattern hasrecently been demanded to have a resolution less than the wavelength.Also, there has been a demand to improve other performance parameters,such as sensitivity. These improvements may compromise the reduction ofthe edge roughness. Therefore, it has been more difficult to reduce theedge roughness while improving the other properties.

Moreover, in the next generation of the devices, the resist pattern bymeans of lithography will be demanded to be much smaller and finer thanever. In such applications, the ratio of the edge roughness generated inthe resist pattern will be relatively increased, since the size of theresist pattern will be smaller and smaller or finer. As a result, theedge roughness will more affect the quality of the devices than ever,especially at the step after forming the resist pattern, such as, anetching step or wiring step, resulting in causing short circuit of thewiring or disconnection of the pattern.

THE OBJECTIVES OF THE INVENTION

Therefore, there is an objective to be solved in this invention. That isa reduction of an edge roughness during forming a fine pattern, whichwas difficult to avoid only by improving a resist material. Such anobjective is solved by that after patterning a resist film, a coatingfilm is formed on the resist film, so as to intermix the resist filmmaterial with the coating film material at the interface therebetween toreduce the edge roughness. In addition to reducing the edge roughness,there is also an objective to keep or improve etching resistance, notonly by using a resist material which is used for irradiation by meansof a light source having a wavelength in the field of a deepultraviolet, such as, an ArF (argon fluoride) excimer laser, but also byusing a resist material which is used for irradiation by means of alight source, such as, KrF (krypton fluoride) excimer laser, and whichis known to have superior etching resistance.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1( a) and (b) show plan views for illustrating processes forpreparing a semiconductor devices, to point out the problems in theconventional steps.

FIG. 2 shows (first) cross-sectional views of the process, forillustrating the principle of the present invention.

FIG. 3 shows (second) cross-sectional views of the process, forillustrating the principle of the present invention.

FIGS. 4( a), (b) and (c) show (first) cross-sectional views forillustrating a method for preparing an EEPROM as one of the applicationsof the present invention.

FIGS. 5( d), (e), and (f) show (second) cross-sectional views forillustrating a method for preparing an EEPROM as one of the applicationsof the present invention.

FIGS. 6( g), (h), and (i) show (third) cross-sectional views forillustrating a method for preparing an EEPROM as one of the applicationsof the present invention.

FIGS. 7( a) and (b) show (fourth) cross-sectional views for illustratinga method for preparing an EEPROM as one of the applications of thepresent invention.

FIGS. 8( a), (b), and (c) show (fifth) cross-sectional views forillustrating a method for preparing an EEPROM as one of the applicationsof the present invention.

FIGS. 9( a), (b), and (c) show plan views from an upper view point forillustrating a method for preparing an EEPROM as one of the applicationsof the present invention.

FIGS. 10( a), (b), (c), and (d) generally show cross-sectional views forillustrating a method for preparing a magnetic head by using a resistpattern formed by the positive type resist composition according to thepresent invention, as an example.

FIG. 11 generally shows a (first) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 12 generally shows a (second) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 13 generally shows a (third) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 14 generally shows a (fourth) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 15 generally shows a (fifth) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 16 generally shows a (sixth) cross-sectional view for illustratinga method for preparing a magnetic head by using a resist pattern formedby the positive type resist composition according to the presentinvention, as an example.

FIG. 17 shows a plan view of a magnetic head prepared in accordance withthe steps shown in FIG. 11 to FIG. 16.

FIG. 18 generally shows an MR element portion in a magnetic head (MRhead), as an example.

FIG. 19 generally shows (first) process for preparing the MR elementportion shown in FIG. 18.

FIG. 20 generally shows a (second) process for preparing the MR elementportion shown in FIG. 18.

FIG. 21 shows a plan view of a situation where a terminal connected toan MR element is formed from two layers of a first resist layer and asecond resist layer.

FIG. 22 shows cross-sectional views at lines of 50-50 and 50′-50′ inFIG. 21.

FIG. 23 shows process views for forming an MR element which is used fora magnetic head (MR head) by means of lifting off process.

FIG. 24 shows process views for forming an MR element which is used fora magnetic head (MR head) by means of lifting off process.

FIG. 25 shows (first) process views for forming an MR element which isused for a magnetic head (MR head), by means of milling process.

FIG. 26 shows (second) process views for forming an MR element which isused for a magnetic head (MR head), by means of milling process.

FIG. 27 shows process views for preparing a T-gate electrode of an HHMT.

FIG. 28 shows (first) process views for preparing a partition wall for aplasma display panel.

FIG. 29 shows (second) process views for preparing a partition wall fora plasma display panel.

FIG. 30 shows an illustrating view of a plasma display panel.

SUMMARY OF THE INVENTION

In order to solve the objectives described above, there is provided thepresent invention as follows.

-   (1) There is provided a resist pattern-improving material,    comprising:    -   (a) a water-soluble or alkali-soluble composition, comprising        -   (i) at least one resin selected from the group consisting of            polyvinyl alcohol, polyvinyl acetal and polyvinyl acetate,            and        -   (ii) at least one crosslinking agent selected from the group            consisting of melamine derivatives, urea derivatives, and            uril derivatives,    -   wherein the resist pattern-improving material is coated on the        surface of the resist pattern to cover it.-   (2) There is provided a resist pattern-improving material in the    formula defined in the paragraph (1), further including a    water-soluble aromatic compound.-   (3) There is provided a resin pattern-improving material in the    formula defined in the paragraph (1) or (2), further including a    surfactant selected from the group consisting of polyoxy    ethylene-polyoxy propylene copolymer, polyoxy alkylene alkyl ethers,    polyoxy ethylene alkyl ethers, polyoxy ethylene derivatives, sorbic    fatty acid esters, glycerin fatty acid esters, primary alcohol    ethoxylates, and phenol ethoxylates, and phenol ethoxylates.-   (4) There is provided a resin pattern-improving material in the    formula defined in any of the paragraphs (1) to (3), further    including a solvent which does not easily dissolve a formed resist    material placed therebelow.-   (5) There is provided a method for reducing an edge roughness of a    resist pattern, wherein after forming the resist pattern, the    pattern-improving material defined in any of the paragraphs (1)    to (4) is coated to cover the resist pattern. Alternatively, there    is provided a method for forming a small and fine pattern by using    the method for reducing the edge roughness of the resist pattern.    Alternatively, there is provided a method for preparing a small    device by means of using the method for reducing the edge roughness    of the resist pattern. Alternatively, there is provided a method for    preparing a semiconductor device by means of using the method for    reducing the edge roughness of the resist pattern.-   (6) There is provided a method for reducing an edge roughness,    comprising:    -   (a) forming a resist pattern;    -   (b) coating a solution including a surfactant selected from the        group consisting of polyoxy ethylene-polyoxy propylene        copolymer, polyoxy alkylene alkyl ethers, polyoxy ethylene alkyl        ethers, polyoxy ethylene derivatives, sorbic fatty acid esters,        glycerin fatty acid esters, primary alcohol ethoxylates, and        phenol ethoxylates, and    -   (c) coating a water-soluble or alkali-soluble composition,        comprising:        -   (i) at least one resin selected from the group consisting of            polyvinyl alcohol, polyvinyl acetal and polyvinyl acetate,        -   (ii) at least one crosslinking agent selected from the group            consisting of melamine derivatives, urea derivatives, and            uril derivatives, and        -   (iii) at least one polyphenol compound selected from the            group consisting of flavonoids, catechins, anthocyanidins,            proanthocyanidins, tannins, quercetins, isoflavones, and            derivatives thereof.

Alternatively, there is provided a method for forming a pattern by meansof using the method for reducing the edge roughness of the resistpattern. Alternatively, there is provided a method for preparing a smalldevice by means of using the method for reducing the edge roughness ofthe resist pattern. Alternatively, there is provided a method forpreparing a semiconductor device by means of using the method forreducing the edge roughness of the resist pattern.

Next, an effect of the present invention and its principle areexplained.

The inventors of the present invention have enthusiastically studied forsolving the objectives stated above. In the middle of the research, theinventors of the present invention have tested various formulas whileadjusting the kinds of the base resin of the resist, the molecularstructures of the protective groups, the balance of hydrophobic andhydrophilic properties, and so on. Finally, the inventors of the presentinvention have found a formula which is able to control the variation ofthe resist pattern size within 10% or less, as well as to reduce theissue of the edge roughness into the level not to cause a problem withrespect to manufacturing.

With reference to FIG. 2 and FIG. 3, the mechanisms of the reduction ofthe edge roughness, and improvement of etching resistance when furtheradding a water-soluble aromatic compound, according to the presentinvention, are explained as follows. See FIG. 2.

FIG. 2 shows a cross-sectional view of the resist pattern, forillustrating a first embodiment. In the first embodiment, the resistpattern is prepared by the process of forming a resist material on thesurface of the base board to form a resist pattern, and then,spin-coating the edge roughness reducing material according to thepresent invention on the base board including the formed openings.

In the first embodiment, the resist pattern-improving material includesa polyvinyl acetal resin (KW-3, made by Sekisui Chemical Co., Ltd.) as abase resin, tetramethoxy methyl glycoluril as a crosslinking agent, anonionic surfactant, pure water (deionized water), and isopropylalcohol. After making a resist pattern, the resist pattern-improvingmaterial according to the present invention is coated, and then,pre-baking is carried out to form a coating film. At the patterninterface therebetween, the resist pattern is mixed with the improvingmaterial according to the present invention, and then, baking is carriedout for crosslinking at a higher temperature than that for thepre-baking, so as to crosslink in the portion where the resist patternis mixed with the improving material. Then it is developed in water or aweak alkali solution. The portion having a weak crosslinking or highsolubility will be removed, to develop and form a fine pattern having areduced roughness. When the resist pattern-improving material furtherincludes a water-soluble aromatic compound, the resist pattern-improvingmaterial having the water-soluble aromatic compound is mixed with theresist pattern to crosslink each other, so as to significantly improveetching resistance, compared with a conventional material comprisingpolyvinyl acetal, polyvinyl alcohol, or polyvinyl acetate. See FIG. 3.

FIG. 3 shows a cross-sectional view of a resist pattern, forillustrating a second embodiment. In the second embodiment, the resistpattern is prepared by the process of forming a resist material on thesurface of the base board to form a resist pattern, and then,spin-coating the edge roughness reducing material on the resist patternincluding the formed openings.

In the second embodiment, the resist pattern-improving material includesa polyvinyl acetal resin (KW-3, made by Sekisui Chemical Co., Ltd.) as abase resin, a nonionic surfactant, pure water (deionized water), andisopropyl alcohol. After forming a resist pattern, the resistpattern-improving material according to the present invention is coated,and then, pre-baking is carried out to form a coating film. At thepattern interface therebetween, the resist is mixed with the improvingmaterial according to the present invention, by heating at a highertemperature than that for the pre-baking. Then, it is developed in wateror a weak alkali solution. The portion having a high solubility, wherethe improving material according to the present invention for reducingthe edge roughness has not permeated, will be removed and developed soas to form a fine pattern having a reduced roughness.

As to a resist material useful for the present invention, it ispreferable to use resist materials for irradiation by a KrF excimerlaser, and alicyclic type resist materials for irradiation by an ArFexcimer laser. The alicyclic type resist materials may include resistmaterials for ArF excimer lithography, such as acrylic type resistmaterials having an adamantyl group on the side chain, COMA type resistmaterials, hybrid type (copolymer of an alicyclic acrylic type and COMAtype) resist materials, cycloolefin type resist materials, and so on.However, the resist materials, which may be used in the presentinvention, are not limited thereto. Novolak type resist materials, PHStype chemical amplified resist materials preferably irradiated by anelectron beam or EUV light source, main chain decomposing typenon-chemical amplified resist materials represented by PMMA, resistmaterials for F2 laser lithography in which any of the above listedresist is fluorinated may be also used in the present invention. Any ofthe resist materials necessary for fine working may be used in thepresent invention. The film thickness of the resist material to beformed may be designed by the surface to be formed and an etchingcondition therefor, and there is no specific limitation in the presentinvention. However, it is preferable to form the resist material havinga film thickness of 0.05 to 200 nm, which is the same as usual.

The base resin used in the present invention may include polyvinylacetal, polyvinyl alcohol, polyvinyl acetate, the polyacrylic acid,polyvinyl pyrrolidone, polyethylene imine, polyethylene oxide,styrene-maleic acid copolymer, polyvinyl amine resin, polyallylamine,water-soluble resin having an oxazoline group, water-soluble melamineresin, water-soluble urea resin, alkyd resin, and sulfonic acid amideresin, and mixture thereof, and so on.

It is not essential to add the crosslinking agent in the secondembodiment. However, the crosslinking agent may be added if necessary,and if so, it may include glycoluril type crosslinking agents; urea typecrosslinking agents, such as, urea resin, alkoxy methylene urea,N-alkoxy methylene urea, ethyleneurea, ethylene urea carboxylic acid,and so on; melamine type crosslinking agents, such as, methylene, alkoxymethylene melamine, and so on; amino type crosslinking agents, such as,benzoguanamine, so long as such a crosslinking agent functions inaccordance with the present invention when it is added in the material.

The water-soluble aromatic compound may include, for example,polyphenols. In detail, such polyphenols may preferably includeflavonoids, catechins, anthocyanidins, proanthocyanidins, tannins,quercetins, isoflavones, and glycosides or derivatives thereof. Inaddition to the polyphenols as stated above, it may be also preferableto use polyhydric phenols represented by resorcin, resorcin [4] arene,pyrogallol, gallic acid, and derivatives thereof, aromatic carboxylicacids represented by salicylic acid, phthalic acid, dihydroxybenzoicacid, and derivatives thereof; naphthalene polyhydric alcoholsrepresented by naphthalenediol, naphthalenetriol, and derivativesthereof; and benzophenone derivatives represented by alizarin yellow A.In addition, it is also possible to use various compounds which havebeen industrially used as a water-soluble pigment having an aromaticgroup.

The surfactant is not necessary to be added if the resistpattern-improving material has affinity or compatibility with theresist. However, it may be added in the following cases: the case wherethe resist pattern-improving material has less affinity or compatibilitywith the resist, the case to control the variation of the pattern sizeas little as possible without adding the crosslinking agent, the case toimprove the uniformity of the roughness reducing property on the surfaceto be treated, the case for deforming, and so on. Such a surfactant maypreferably be selected from the group consisting of nonionicsurfactants, such as, polyoxy ethylene-polyoxy propylene copolymers,polyoxy alkylene alkyl ethers, polyoxy ethylene alkyl ethers, polyoxyethylene derivatives, sorbic fatty acid esters, glycerin fatty acidesters, primary alcohol ethoxylates, and phenol ethoxylates. Inaddition, so long as using a nonionic surfactant, any nonionicsurfactant other than the listed here may be used, and such alternativeswill be expected to accomplish the same effect in a similar manner asstated above.

In addition to the resin, the crosslinking agent (which is not essentialto the present invention), and the water-soluble aromatic compound(which is not essential to the present invention), the resistpattern-improving material according to the present invention mayinclude at least one organic solvent selected from the group consistingof alcohols, linear esters, cyclic esters, ketones, linear ethers, andcyclic ethers If the resist pattern-improving material according to thepresent invention has an insufficient solubility to dissolve the soluteincluded therein, or has an insufficient property of reducing the edgeroughness, it is preferable to add such an organic solvent to the extentnot to affect the forming of the resist pattern. In such a case, theorganic solvent as the alcohols may include isopropyl alcohol. Theorganic solvent as the linear esters may include lactic acid ethyl(ethyl lactate), propylene glycol methyl ether acetate (PGMEA). Theorganic solvent as the cyclic esters may include lactones. Inparticular, it is preferable to use γ-butyrolactone. The organic solventas the ketones may include acetone, cyclohexanone, heptanone, and so on.The organic solvent as the linear ethers may include ethylene glycoldimethyl ether, and so on. The organic solvent as the cyclic ethers mayinclude tetrahydrofuran, dioxane, and so on. Especially, it ispreferable to use an organic solvent which has a boiling point of 80 to200° C., approximately. Fine drawing of the resist pattern may beaccomplished by using such an organic solvent having the boiling pointwithin this range.

EXAMPLE TEST 1 Preparation of a Resist Pattern-Improving Material

Various resist pattern-improving materials were prepared in accordanceof the formulas shown in the Table 1 below. In Table 1, the numbersencompassed by parentheses are based on parts by weight. KW-3 made bySekisui Chemical Co., Ltd. is used as polyvinyl acetal resin, and thesurfactant used here is made by Asahi Denka Co., Ltd. Pure water(deionized water) and isopropyl alcohol in a ratio of 98 6:0.4, byweight, was mixed as the main solvent. In Table 1, “Uril” meanstetramethoxy methyl glycoluril, and “Urea” means N,N′-dimethoxy methyldimethoxy ethyleneurea, and “Melamine” means hexamethoxy methylmelamine.

TABLE 1 The Name of the Water-soluble Resist Pattern- CrosslinkingAromatic improving Material Agent Compound Surfactant A KW-3 (16) Uril(0.8) Not Included Not Included B KW-3 (16) Urea (1.0) Not Included NotIncluded C KW-3 (13), Melamine (0.5) Not Included Not Included PVA (3) DKW-3 (16) Uril (1.2) Not Included Not Included E KW-3 (16) Uril (0) NotIncluded Not included F KW-3 (16) Uril (1.0) Not Included Not Included GKW-3 (16) Uril (1.0) Not Included TN-80 (0.0625) H KW-3 (16) Uril (1.0)Not Included TN-80 (0.125) I KW-3 (16) Urea (1.0) catechin (5) NotIncluded J KW-3 (16) Urea (1.0) catechin (5) PC-8 (0.05)

While coating the resist pattern-improving material to form a film,spin-coating is carried out in the process of rotating at a speed of1000 rpm for a period of 5 seconds followed by rotating at a speed of3500 rpm for a period of 5 seconds. In the baking step, the sample isheated at a temperature of 85° C. for a period of 70 seconds, followedby heating at a temperature of 90 to 100° C. for a period of 70 seconds.Then, the sample was washed with pure water for a period of 60 secondsso as to remove a non-crosslinked portion.

EXAMPLE TEST 2 Test for Reducing the Edge Roughness of the ResistPattern

The various resist pattern-improving materials prepared in accordancewith Example 1 were used here. 150 nm space pattern, which were formedby using an alicyclic resist for ArF lithography, were treated in thisexample. As a result, the patterns which had improved roughness wereobtained.

TABLE 2 Roughness Size The Name of the Initial after the IncreasedAmount Resist Pattern- Roughness Size Treatment of the Size improvingMaterial (3 sigma, nm) (3 sigma, nm) (nm) A 16.0 12.2 10.8 B 16.0 10.09.1 C 16.0 8.5 6.5 D 16.0 6.0 6.8 E 16.0 15.0 9.2 F 16.0 11.0 7.4 G 16.05.8 9.1 H 16.0 5.5 13.8 I 16.0 11.3 5.8 J 16.0 7.1 10.9

EXAMPLE TEST 3 Test for Reducing the Edge Roughness of the ResistPattern

The various resist pattern-improving materials prepared in accordancewith Example 1 were used here 150 nm hole patterns, which were formed byusing an alicyclic resist for ArF lithography, were treated in thisexample. As a result, the patterns which had improved roughness wereobtained.

TABLE 3 Roughness Size The Name of the Initial after the IncreasedAmount Resist Pattern- Roughness Size Treatment of the Size improvingMaterial (3 sigma, nm) (3 sigma, nm) (nm) A 8.2 7.5 17.5 B 8.2 6.8 3.0 C8.2 5.9 11.5 D 8.2 4.0 1.8 E 8.2 8.0 7.3 F 8.2 7.8 16.8 G 8.2 4.2 1.6 H8.2 4.1 6.8 I 8.2 7.7 4.8 J 8.2 4.5 8.8

From the results of Example 2 and Example 3, the effect of reducing theedge roughness indicates that the resist pattern-improving materialaccording to the present invention is applicable either for linedpatterns and holed patterns

EXAMPLE TEST 4 Etching Resisitance

The resist films having a thickness of 0.5 micron were formed on asilicon wafer, and then treated by the resist pattern-improvingmaterials D, H, I prepared in the previous Example. For comparison, as aKrF resist, a sample formed from UV-6 made by Shiplay Corporation, and asample formed from PMMA (polymethyl methacrylate) were prepared. Usingan RIE equipment in the type of parallel electrodes, each sample wasetched under the conditions of RF power=200 W, at a pressure of 0.02Torr, using CF₄ gas for a period of 3 minutes. Then, the amounts ofreduced film thickness were compared.

TABLE 4 The Material Name Etching Plate (Å/s) Ratio UV-6 627 1.00 PMMA770 1.23 I 650 1.04 J 662 1.06

The results listed above show that the etching resistance of the resistpattern-improving material according to the present invention is similarto that of the KrF resist, and significantly improved compared withPMMA.

EXAMPLE TEST 5 Application to an Electron Ray

PMMA (polymethyl methacrylate) was used as a resist material, and 100 nmspace patterns were formed by an electron beam exposure apparatus (50KeV). The resist were treated to obtain patterns having a reducedroughness as follows.

TABLE 5 Initial Roughness Size Increased Amount Roughness Size after theTreatment of the Size Resist Pattern (3 sigma, nm) (3 sigma, nm) (nm) A18.0 14.5 7.8 B 18.0 12.0 8.0 C 18.0 11.2 4.2 D 18.0 8.0 4.3 E 18.0 16.55.9 F 18.0 13.5 9.3 G 18.0 6.3 7.8 H 18.0 6.1 22.3 I 18.0 14.1 4.3 J18.0 9.1 9.2

The results show that the resist pattern-improving material according tothe present invention does not restrict the selection of the type of theresist material, and may be applicable either to chemical amplified typeresist materials and chemical non-amplified type resist materials.

EXAMPLE TEST 6 Application to a Two Layers for Irradiating an ElectronRay

PMMA (polymethyl methacrylate) was coated to have a thickness of 0.15micron, to form a first layer as a resist. Then, ZEP-520A was coatedthereon to have a thickness of 0.15 micron, to form a second layer.Thereby obtained sample boards were subjected to photo irradiation atthe space patterns by electron beam exposure apparatus (50 KeV).Development was performed in MIBK (methyl isobutyl ketone) for 60seconds, so as to obtain a pattern having a width of 100 nm. Therebyobtained resist was subjected to treatment using the resistpattern-improving materials D, G, H, which had indicated preferableresults obtained in Example 7. The results obtained in this Example showthat no affect was found on the upper layer, ZEP layer. However, thelower layer, PMMA layer, was affected, and the edge roughness of thepattern is reduced.

The examples described above show that the resist pattern-improvingmaterial according to the present invention may be useful in variousapplications. Several applications of the present invention statedhereinafter are based on the fact revealed by these Example Tests. Thepresent invention will be explained with respect to a method forpreparing a flash type EEEPROM, a method for preparing a magneticsensors and a method for preparing a PDP (Plasma Display Panel).However, the present invention may be applicable to any otherapplications in which a fine pattern is necessary, and is not limitedthereto. As the other applications, a method for preparing functionalparts, such as, mask pattern, rectil pattern, LCD (liquid crystallinedisplay), SAW filter (Surface Acoustic Wave filter), and so on; a methodfor preparing optical parts used for connecting optical wiring; a methodfor preparing fine and small parts, such as, micro-actuator, and so onmay be included. Also, as an example of a method for preparingsemiconductor devices, a process for preparing a flash memory will beexplained in detail, but the present invention is not limited thereto.The present invention may be also applicable to a method for preparing alogic device, DRAM, FRAM, and so on, and same effect will be expected ina manner as stated above.

DETAILED DESCRIPTION OF THE INVENTION

The technology of the resist pattern-improving material according to thepresent invention may be useful for various applications, among whichseveral methods for preparing various devices are explained here.

(1) First Application Example of the Present Invention: A Method forPreparing a Flash Memory

There is provided a method for preparing a flash memory. This is anexample for preparing a semiconductor device, which may be preferable toincorporate the step for forming a pattern according to the presentinvention. For example, the resist pattern-improving material accordingto the present invention may be used in the step of forming a holedpattern, which may contribute to reduce an edge roughness of the resistpattern, and thereby, the size of the inner diameter of the holedpattern, the width between the linier patterns and/or separatedpatterns, and the interval between the linear patterns, and so on, maybe controlled within the allowable range

As shown in FIG. 4( a), a field oxide film 23 of SiO₂ is selectivelyformed on an element separation region on a p-type silicon wafer. Then,a first gate insulation film 24 a of a MOS transistor located in amemory cell portion (a first element region), is formed by heatoxidation in a step, the first gate insulating film 24 a having a filmthickness of 100 to 300 Å, and a second gate insulation film 24 b of aMOS transistor located in a peripheral circuit portion (a second elementregion) is formed by heat oxidation in another step, the second gateinsulating film 24 b having a film thickness of 100 to 500 Å. However,if both of the first and second gate insulation films 24 a, 24 b aredesigned to have the same thicknesses, those oxidation films may beconcurrently formed in one step.

Then, a MOS transistor having a type of n-type depression channel isformed on the memory cell portion. In order to control a thresholdvoltage, the peripheral portion is masked by a resist film 26, and then,phosphorous (P) or arsenic (As) as an n-type impurity is incorporatedinto a portion to be a channel region which will be located right belowa floating gate electrode, by means of ion implantation at a dose amountof 1×10¹¹ to 1×10¹⁴ cm⁻², and thereby, a first threshold controllinglayer 25 a is formed. At that time, the dose amount and the selection ofthe conductive type of the impurity may be determined according towhether it is a depression type or accumulation type.

Then, a MOS transistor having a type of n-type depression channel isformed on the peripheral circuit portion. In order to control athreshold voltage, the memory cell portion is masked by a resist film27, and then, phosphorous (P) or arsenic (AS) as an n-type impurity isincorporated into a portion to be a channel region which will be locatedright below a gate electrode, by means of ion implantation at a doseamount of 1×10¹¹ to 1×10¹⁴ cm⁻², and thereby, a second thresholdcontrolling layer 25 b is formed See FIG. 4( b)

Following the above, a first polysilicon film (first conductive layer)28 is formed on the whole of the surface, the first polysilicon filmhaving a film thickness of 500 to 2000 Å. The first polysilicon filmwill be a floating gate electrode of a MOS transistor in the memory cellportion, and a gate electrode of a MOS transistor in the peripheralcircuit portion. See FIG. 4( c).

Then, a resist film 29 is used as a mask on the first polysilicon film28 to make a pattern, and thereby, the floating gate electrode 28 a isformed on the MOS transistor in the memory cell portion. See FIG. 5( d).At that time, as shown in FIG. 7( a), the patterning is performed in amanner such that the width in the direction of “X” is a final size,without patterning in the direction of “Y” to continue to cover theregion to be a source drain region.

Then, the resist film 29 is removed, followed by that the floatingelectrode 28 a is covered by means of heat oxidation so as to form acapacitor insulation film 30 a of SiO₂ having a film thickness of 200 to500 Å. At that time, the SiO₂ film 30 b of is formed concurrently on thefirst polysilicon film 28 of the peripheral circuit portion. Optionally,a couple of layers, including SiO₂ and Si₃ N₄ films may be formed as thecapacitor insulation film. Then, the floating gate electrode 28 a andthe capacitor insulation film 30 a are covered to form a secondpolysilicon film (second conductive film) 31 having a film thickness of500 to 2000 Å, which will be a control gate electrode. See FIG. 5( e).

Following the above, the memory cell portion is masked by a resist film32, and then, the second polysilicon film 31 and the SiO₂ film 30 b inthe peripheral circuit portion are continuously removed to reveal thefirst polysilicon film 28. See FIG. 5( f).

Then, the second polysilicon film 31, the SiO₂ film 30 b, and the firstpolysilicon film 28 a patterning only in the direction of “X”, which islocated in the memory cell portion, are masked with a resist film 32,followed by that patterning is performed in the direction of “Y” to havea final size of a first gate portion 33 a. The control gate electrode 31a, the capacitor insulation film 30 c, and the floating gate electrode28 c are formed to have a width in the direction of “Y” being about 1μm. The first polysilicon film 28 in the peripheral portion is maskedwith a resist 32, and then, patterning is carried out to have a finalsize of a second gate portion 33 b, so as to obtain a gate electrode 28b having a width of about 1 μm. See FIG. 6( g) and FIG. 7( b).

Then, while operating the control gate electrode 31 a, capacitorinsulation film 30 a, and floating gate electrode 28 a in the memorycell portion as a mask, phosphorous (P) or arsenic (As) is incorporatedinto the Si base board 22 of an element forming region at a dose amountof 1×10¹⁴ to 1×10¹⁶ cm⁻², so as to obtain an n-type source drain region35 a, 35 b. Also, while operating the gate electrode 28 b in theperipheral portion as a mask, phosphorous (P) or arsenic (As) isincorporated into the Si base board 22 of an element forming region at adose amount of 1×10¹⁴ to 1×10¹⁶ cm⁻², so as to obtain a S/D region layer36 a, 36 b. See FIG. 6( h).

Then, a layer insulation film 37 of a PSG film having a film thicknessof 5000 Å, approximately, is formed to cover the first gate portion 33 ain the memory cell portion and the second gate portion 33 b in theperipheral circuit portion. Subsequently, contact holes 38 a, 38 b, 39a, 39 b are formed on the layer insulation film 37 above the sourcedrain region layers 35 a, 35 b, 36 a, 36 b, and then, S/D electrodes 40a, 40 b, 41 a, 41 b are formed to complete a flash type EEPROM. See FIG.6( i).

As described above, in the first application example of the presentinvention, the patterned first polysilicon film 28 a in the memory cellportion is covered with the capacitor insulation film 30 a, as shown inFIG. 5( e). Then, the second polysilicon film 31 is formed on the memorycell portion and peripheral circuit portion, and then, as shown in FIG.6( g), patterning is continuously performed to form the first gateportion 33 a comprising the first gate insulation film, 24 a, floatinggate electrode 28 c, and capacitor insulation film 30 c, and controlgate electrode 31 a.

Therefore, the formed capacitor insulation film 30 c is completelyprotected by the first and second polysilicon films 28 a, 31. See FIG.5( e) and (f). Thus, the capacitor insulation film 30 c is preventedfrom contaminating any particles and the like, so as to form a capacitorinsulation film 30 c for covering the floating gate electrode 28 c in agood quality.

In addition, the formed second gate insulation film 24 b in theperipheral circuit portion, is completely covered with the firstpolysilicon film 28 See FIG. 4( c) to FIG. 5( f). Thus, the second gateinsulation film 24 b continues to have the same film thickness since itwas formed As a result, it is easy to control the film thickness of thesecond gate insulation film 24 b. Also, it is easy to adjust theconcentration of the conductive impurity for controlling the thresholdvoltage.

In the first application example, the first gate portion 33 a is formedby patterning in the direction of the gate width to have a width in thedirection thereof, and then, patterning in the direction of the gatelength, so as to obtain a final gate width. Alternatively, the firstgate portion 33 a is formed by patterning in the direction of the gatelength to have a width, and then in the direction thereof, patterning inthe direction of the gate width in the direction thereof, so as toobtain a final gate width.

(2) The Second Application Example: A Method for Preparing a FlashMemory FIGS. 8( a) to (c) show cross-sectional views for illustrating amethod for preparing a flash type EEPROM referred to as “FLOTOX Type” or“ETOX Type”, as the second application example of the present invention.The left figures show cross-sectional views illustrating a memory cellportions shown in the direction of “X” (gate length), where a MOStransistor is formed having a floating gate electrode. The centralfigures show cross-sectional views of the memory cell portion in theleft figures, shown in the direction of “Y” (that is a gate widthdirection perpendicular to the “X” direction). The right figures showcross-sectional views of a MOS transistor in a peripheral circuitportion.

The points of the second application example, which are different fromthe first application, are as follows. FIG. 5( f) is for the firstapplication example. After the step shown in FIG. 5( f), the secondapplication example has a step of forming a metal film 42 having a highmelting temperature (fourth conductive film) 42, such as, a W or Ti filmhaving a film thickness of about 2000 Å, on the first polysilicon film28 in the peripheral circuit portion and the second polysilicon film 31in the memory cell portion, and thereby obtaining a polyside film.Subsequent to the above, the second application example includes thesimilar steps shown in FIGS. 6( g) to (i) to complete a flash typeEEPROM. That is, while using the resist film 43 as a mask with respectto the high melting temperature metal film 42, the second polysiliconfilm 31, the SiO₂ film 30 b, and the first polysilicon film 28 apattered only in the direction of “X”. Then, patterning in the directionof “Y” is performed to have a final size of the first gate portion 44 a,so as to form a control gate electrode 42 a, 31 a, capacitor insulationfilm 30 c, and floating gate electrode 28 c, having a width in thedirection of ‘Y” of about 1 μm, on the memory cell portion. In addition,while using the resist film 43 as a mask with respect to the highmelting temperature metal film 42 and first polysilicon film 28,patterning is performed to have a final size of the second gate portion44 b, so as to form a gate electrode 42 b, 28 b having a width of 1 μm,approximately, on the peripheral circuit portion. See FIG. 8( b).

Then, while using the control gate electrode 42 a, 31 a, capacitorinsulation film 30 a, and the floating gate electrode 28 a of the memorycell portion as a mask, phosphorous (P) or arsenic (As) is incorporatedby means of ion implantation into the Si base board 22 of an elementforming region at a dose amount of 1×10¹⁴ to 1×10¹⁶ cm⁻², so as toobtain an n-type source drain region 45 a, 45 b. Also, while using thegate electrode 42 b, 28 b in the peripheral circuit portion as a mask,phosphorous (P) or arsenic (As) is incorporated by means of ionimplantation into the Si base board 22 of an element forming region at adose amount of 1×10¹⁴ to 1×10¹⁶ cm⁻², so as to obtain a source drainregion layer 46 a, 46 b.

Then, a layer insulation film 37 of a PSG film having a film thicknessof 5000 Å, approximately, is formed to cover the first gate portion 44 ain the memory cell portion and the second gate portion 44 b in theperipheral circuit portion. Subsequently, contact holes 48 a, 48 b, 49a, 49 b are formed on the layer insulation film 47 above the sourcedrain region layers 45 a, 45 b, 46 a, 46 b, and then, S/D electrodes 50a, 50 b, 51 a, 51 bare formed to complete a flash type EEPROM. See FIG.8( c). The same portions as described in the first application exampleare shown by the same symbols as used in the first application example.

According to the second application example of the present invention, ahigh melting temperature metal film 42 a and 31 a is formed on thepolysilicon film for the control gate electrode 42 a, 31 a, and the gateelectrode 42 b, 28 b, resulting in further reducing electricalconductivity.

In addition, in the second application example described here, a highmelting temperature metal films 42 a, 42 b are used as the fourthconductive film on the polysilicon film. However, a high meltingtemperature metal silicide such as titanium silicide (TiSi) may be used.

(3) Third Application of the Present Invention: A Method for Preparing aFlash Memory

FIGS. 9( a) to (c) show cross-sectional views of the third applicationexample of the present invention for illustrating a method for preparinga flash type EEPROM referred to as “FLOTOX Type” or “ETOX Type”. Theleft figures show cross-sectional views of a memory cell portion shownin the direction of “X” (gate length), where a MOS transistor is formedhaving a floating gate electrode. The central figures showcross-sectional views of the memory cell portion in the left figures,shown in the direction of “Y” (that is the gate width directionperpendicular to the “X” direction). The right figures showcross-sectional views of a MOS transistor in a peripheral circuitportion.

The points of the third application example, which are different fromthose of the first application example, are as follows. The second gateportion 33 c in the peripheral circuit portion (the second elementregion) has a construction of the first polysilicon film (firstconductive film) 28 b, the SiO₂ film (capacitor insulation film) 30 d,and the second polysilicon film (second conductive film) 31 b, whoseconstruction is similar to the first gate portion 33 a in the memorycell portion (first element region). By the steps shown in FIG. 9( b) orFIG. 9( c), the first and second polysilicon films 28 b, 31 b are shortcircuited to obtain the gate electrode.

In other words, an opening portion 52 a, as shown in FIG. 9( b), isformed to penetrate the second polysilicon film 31 b as the upper layer,the SiO₂ film 30 d, and the first polysilicon film 28 b as the lowerlayer. The opening portion 52 a is formed on a portion other than theportion to form the second gate portion 33 c as shown in FIG. 9( a), andfor example, the opening portion 52 a is formed on an insulation film54. Inside opening portion 52 a, a third conductive film, such as a highmelting temperature metal film of W film or Ti film, is buried, so as togenerate a short circuit between the first and second polysilicon films28 b, 31 b.

Alternatively, an opening portion 52 a, as shown in FIG. 9( c), isformed to penetrate the second polysilicon film 31 b as the upper layer,and the SiO₂ film 30 d. On the bottom surface of the opening 52 a, thefirst polysilicon film 28 b as the lower layer is revealed. Thereafter,inside the opening portion 52 a, a third conductive film, such as a highmelting temperature metal film of W film or Ti film, is buried, so as togenerate a short circuit between the first and second polysilicon films28 b, 31 b.

According to the third application example of the present invention, thesecond gate portion 33 c in the peripheral circuit portion has the sameconstruction as the first gate portion 33 a in the memory cell portion.Thus, the memory cell portion and the peripheral circuit portion may beformed concurrently, resulting in simplifying the manufacturing steps.

In addition, in the third application example described here, the thirdconductive film 53 a or 53 b is formed in a step different from the stepfor forming the fourth conductive film described in the secondapplication example. However, they may be formed concurrently if theyare made of the common high melting temperature metal film.

(4) The Fourth Application Example of the Present Invention: A Methodfor Preparing a Magnetic Head

The fourth application example of the present invention relates to amethod for preparing a magnetic head, that is one of applications of theresist pattern-improving material having reduced edge roughness. In thefourth application example, the resist pattern-improving materialaccording to the present invention is applied to the resist pattern 302,326 formed from a positive type resist.

FIGS. 10(A) to (D) show process views stepwise illustrating the methodfor preparing a magnetic head.

First of all, a resist film having a thickness of 6 μm, as shown in FIG.10(A), is formed on a layer insulation layer 300, followed by beingirradiated and developed to form a resist pattern 302 having an opeingpattern which will be used for forming a thin film magnetic coil in ashape of spiral.

Then, as shown in FIG. 10(B), a plating surface preparation layer 306 isformed either on a portions with the resist pattern 302 and a portionwithout the resist pattern (the opening portion 304), on the layerinsulation layer 300. The plating surface preparation layer 306 iscomposed of a Ti layer having a thickness of 0.01 μm and a Cu layerhaving a thickness of 0.05 μm, which are formed by means of deposition.

Then, as shown in FIG. 10(C), a thin film conductor 308 is formed on aportion without forming the resist pattern 302, where the platingsurface preparation layer 306 is formed on the opening portion 304. Thethin film conductor 308 is made of a Cu plating film having a thicknessof 3 μm.

Then, as shown in FIG. 10(D), the resist pattern 302 is removed orlifted off by means of dissolution from the layer insulation layer 300,to obtain a thin film magnetic coil 310 made of a thin film conductor308 having a spiral pattern.

As described above, the magnetic head is prepared.

Thereby obtained magnetic head is prepared by using the resist pattern302 as a mask whose edge roughness is reduced by the resistpattern-improving material according to the present invention, andtherefore, it has a spiral shape having reduced edge roughness. The thinfilm magnetic coil 310 has a very small pattern, but it is made finely,and in addition, it is superior in mass production.

FIGS. 11 to 16 shows process views for illustrating various magneticheads.

As shown in FIG. 11, a gap layer 314 is coated and formed on anon-magnetic base board of a ceramics by means of spattering. On thenon-magnetic base board 312, an insulating layer of silicon oxide and aninsulating surface preparation layer of Ni—Fe permalloy are previouslycoated and formed by means of spattering, which are not shown in thefigures. Moreover, a magnetic layer of Ni—Fe permalloy as a lower layeris previously formed. A resin insulating film 316 of a heat curableresin is formed on a predetermined portion of the gap layer 314 otherthan the portion to be a magnetic tip portion of the magnetic layer asthe lower layer, not shown in the figures. Then, a positive type resistcomposition is coated on the resin insulating film 316 to form a resistfilm 318.

Then, the resist film 318 is irradiated and developed to form a spiralpattern as shown in FIG. 12 Thereafter, the resist film having a spiralshape is subjected to a heat curing treatment at a temperature of acouple of hundreds degree in Celsius for a period of 1 hour, so as toform a first spiral shaped pattern 320 having protrusions. On thesurface, a conductive surface preparation layer 322 of Cu is furtherformed.

Then, as shown in FIG. 14, a positive type resist composition isspin-coated on the conductive surface preparation layer 322 so as toform a resist film 324 Thereafter, the resist film 324 is patterned onthe first spiral shaped pattern 320, so as to obtain a resist pattern326.

Then, as shown in FIG. 15, a Cu conductive layer 328 is formed, by meansof plating, on the revealed surface of the conductive surfacepreparation layer 322, that is a portion where the resist pattern 326 isnot formed. Thereafter, as shown in FIG. 16, the resist pattern 326 isremoved or lifted off, by means of dissolution, from the conductivesurface preparation layer 322 to obtain a thin magnetic coil 330 of theCu conductive layer 328 having a spiral shape.

As described above, there is prepared a magnetic head having a writablemagnetic pole 332 of the magnetic layer formed on a resin insulatinglayer 316, and a thin film magnetic coil 330 on its surface, as shown ina plan view of FIG. 17. The pattern of the writable magnetic pole 332 ofthe magnetic layer is formed in a manner that a positive type resist islocated as the upper layer, and a novolac type resist is located as thelower layer. Such an upper layer pattern formed by irradiation anddevelopment is vertically transferred on the lower layer by means of anenzyme plasma. Then, a plating film is formed followed by removing theresist and etching the plated base

Since thereby obtained magnetic head is formed by using a resist pattern326 whose edge roughness is reduced by the resist pattern-improvingmaterial according to the present invention. The spiral pattern of themagnetic head is very small but formed finely. The tip portion of thewritable magnetic pole 332, composed of the thin film magnetic coil 330and the magnetic layer, has a very small and fine size and a high aspectratio, and also is superior in mass production.

An MR element portion 11 is formed to be provided with a terminal 12 ofa magnetic head (MR type head) as shown in FIG. 18, as follows. As shownin FIG. 19( a), an alumina layer 221 is provided on a supportingmaterial 211, on which a lower shield layer 231 of NiFe and a lower gaplayer 241 of alumina are continuously formed. Further, on the lower gaplayer 241, a first resist layer 261 is formed above the surface of thebase board having an MR pattern 251. Then, the base board having thefirst resist layer 261 formed is subjected to irradiation of amonochromatic light 271 on the whole surface thereof to improve itssurface, as shown in FIG. 19( c). This step is intended to prevent thesurface layer from mixing with the second resist layer formed thereon.On the first resist layer 261 whose surface is improved, a second resistlayer 29 is formed, as shown in FIG. 19( c). Thereafter, using aphoto-mask having a predetermined pattern, an i ray is selectivelyirradiated. In FIG. 19( c), the irradiated portions 311, 321 areremained. After the irradiation, baking is performed, and then, it isdeveloped.

As a result, a resist pattern, whose condition is that a pattern 261′ ofthe first resist layer 261 is eroded under the pattern 291′ of thesecond resist layer 291, is formed, as shown in FIG. 20( d). As shown inFIG. 20( e), the lower portion of the resist pattern on the MR element251 may be formed into a hollow. Thereafter, a terminal forming material331 is formed into a film on the surface of the base board having thetwo layer resist pattern, as shown in FIG. 20( f). Then, the two layerresist pattern is dissolved and selectively removed in a solution fordevelopment, so as to form a pattern of the terminal forming material331 at a portion where the two layer resist pattern is not provided.Here, the MR pattern 251 corresponds to the MR element portion 11 shownin FIG. 18, and the pattern of the terminal forming material 331corresponds to the terminal 12 shown in FIG. 18.

Then, see FIG. 21 and FIG. 22. Explanation here is focused on a processof a hollow lifting off. FIG. 21 shows a plan view of a situation wherea terminal 421 connected to an MR element 411 is formed by using twolayers of the first resist layer 431 and the second resist layer 441.The first resist layer 431 is eroded under the second resist layer 441,whose periphery is drawn by a dashed line. The lower figure in FIG. 21shows a magnified view of the MR element 411, which corresponds to theportion pointed out by a symbol “A” in the upper figure in FIG. 21. Inthe lower figure of FIG. 21, the periphery of the first resist layer 431under the second resist layer 441 is shown by a dashed line. Above theMR element 411, only the second resist layer 441 exists, between whichthere is a hollow. As shown by a cross-sectional view of FIG. 22, theupper figure in FIG. 22 shows a cross-sectional view at a line 50-50pointed out in the lower figure of FIG. 21, which illustrates a hollowstructure between the MR element 411 and the second resist layer 441.The lower figure in FIG. 22 shows a cross-sectional view at a line50′-50′ pointed out in the lower figure in FIG. 21, which illustratesthe second resist layer 441 formed on the first resist layer 431provided on the base board 401. As shown in the upper figure in FIG. 22and the lower figure in FIG. 22, a film 421 of the terminal formingmaterial on the second resist layer 441 will be removed or lifted offtogether with the two layers of the first resist layer 431 and thesecond resist layer 441, when a lifting off treatment is performed

For example, there is provided a method for preparing an MR element fora magnetic head (MR head) by means of the lifting off process. As shownin FIG. 23( a), an alumina layer 62 is provided on a supporting material61, on which a lower shield layer 63 of NiFe and a lower gap layer 64 ofalumina are continuously formed, so as to prepare a base board having anMR film 65 on the lower gap layer 64 for producing an MR element. Then,the MR film 65 on the surface of the base board is patterned to preparean MR element 66 as shown in FIG. 23( b). Continuously, as shown in FIG.23( c), a terminal 68 is formed on the lower gap layer 64 on the baseboard, by using a mask pattern 67. Then, the mask pattern 67 is removedby means of the lifting off process, as shown in FIG. 23( d).Thereafter, as shown in FIG. 23( e), the lower shield layer 63 and thelower gap layer 64 are patterned by means of ion trimming, so as toobtain the lower shield layer 63′ and the lower gap layer 64′.Alternatively, the lower shield layer 63′ and the lower gap layer 64′may be formed by patterning on the base board as shown in FIG. 24( a),and then, the MR element 66 may be formed and the terminal 68 may beformed by means of lifting off as shown in FIG. 24( b), and then thelower shield layer 63′ and the lower gap layer 64′ may be patterned asshown in FIG. 24( c), and thereby, the final shape of the lower shieldlayer 63 and the lower gap layer 64 may be obtained.

Then, there is provided another method for preparing a magnetic head,with reference to FIG. 25 and FIG. 26. As shown in FIG. 25( a), a baseboard is prepared which has a lower shield layer 83 of NiFe, a lower gaplayer 84 of alumina, and an MR film 85 for an ER element continuouslyformed on an alumina layer (not shown) provided on a supporting material(not shown) On the base board, polymethyl glutalimide made by JapanMacdermid Corporation as a material for the first resist layer isspin-coated to have a thickness of 0.3 μm, followed by baking at atemperature of 180° C. for a period of 2 minutes, so as to form a firstresist layer 86. Then, the base board is placed on a hot plate inside achamber for surface treatment, followed by irradiating a light (Xe₂excimer light) having a wavelength of 172 nm on the whole surface of thebase board at an irradiation length of 1 mm for a period of 20 seconds.Then, the base board is moved into a coating cup again, and then, thepositive type resist composition according to the present invention isspin-coated thereon to have a thickness of 2.0 nm, followed by baking ata temperature of 110° C. for a period of 2 minutes, so as to form asecond resist layer 87. Continuously, as shown in FIG. 25( c), an i ray88 is irradiated through a predetermined mask pattern formed by a g rayspattering. After the irradiation, it is developed by a solution oftetramethyl ammonium hydroxide at a concentration of 2.38% by mass. Atthe time of development, the first resist layer 86 and the second resistlayer 87 are concurrently developed so as to form two layer resistpattern 89 as shown in FIG. 25( d). Observation of the structure of thetwo layer resist pattern 89 by an optical microscope shows that thelower layer is eroded under the upper layer. Then, as shown in FIG. 26(e), the two layer resist pattern 89 is masked to pattern by means of ionmilling to form an MR element 85 a, followed by that a metal film 81 tobe a terminal is formed by means of spattering as shown in FIG. 26( f).Then, the two layer resist pattern 89 is removed by a resist removingagent (MS-2001 made by Fuji Hunt Corporation), followed by washing withethanol and drying to form a terminal 81.

(5) The Fifth Application Example of the Present Invention: A Method forPreparing an HEMT

There is provided a method for preparing an HEMT as an example of theapplications for the resist pattern-improving material according to thepresent invention. In this application example, a resist patterns formedfrom a positive type resist 91, 94 are formed by using the resistpattern-improving material according to the present invention forreducing the edge roughness.

FIG. 27 shows process views illustrating a method for preparing a T-gateelectrode of an HEMT. As shown in FIG. 27( a), there is prepared a GaAsbase board 90 having a buffer epitaxial layer, an epitaxial layer forsupplying second electrons, and a cap epitaxial layer formed thereon. Onthe GaAs base board 90, a negative type first electron beam resist(SAL-601 made by Shipley Corporation) is coated, followed by baking.Thereafter, an electron beam is irradiated to form a resist pattern 91having a separated line shape. The resist pattern 91 has a gate lengthof 0.1 μm and a thickness of 1 μm. After the irradiation, the negativetype first electron beam resist is developed, followed by washing anddrying to obtain a resist pattern 91 having a separated line shape, theresist pattern 91 having a gate length of 0.1 μm and a thickness of 1μm. Then, as shown in FIG. 27( b), the base board is treated by anenzyme plasma (for example, at an electric power of 100 W, at a periodof 30 seconds, at an oxygen flow rate of 200 sccm) in order to improveits wettability Then, as shown in FIG. 27( c), an OCD (made by TokyoOhka Kogyo Co, Ltd.), that is an insulate spin-on-glass (SOG) is coatedon the GaAs base board 90 at a thickness of 0.5 μm, followed by bakingat a temperature of 110° C. for a period of 2 hours. Thus, an insulationfilm 92 is formed. Thereafter, an O₂-Assher is used for removing theresist pattern 91 having a separated line shape, so as to form anopening 92 a whose cross-section has a taper shape (the angle of thetaper: 60 degree.) Then, as shown in FIG. 27( d), TiW is coated by meansof spattering to have a thickness of 0.1 μm, on the whole surface of theGaAs base board, so as to form a first metal wiring layer 93 which willbe used for a lower gate electrode. On the first metal wiring layer 93,a positive type resist is coated to have a thickness of 0.6 μm, followedby baking to form a resist layer 94. Thereafter, an irradiation anddevelopment of the resist 94 are carried out followed by washing anddrying, so as to form an opening 94 a larger than the opening 92 a,whose cross-section has an opposite-taper shape. The opening 94 a has agate length of 0.5 μm. Thereafter, Ti and Al are continuously depositedto have a thickness of 0.5 μm on the GaAs base board, so as to form asecond metal wiring layer 95 which will be used for an upper gateelectrode. As shown in FIG. 27( e), the portion having the second metalwiring layer 95 formed on the opening 92 a is remained, and the otherportion of the second metal wiring layer 95 and the resist layer 94thereunder are removed or lifted off by using an organic solvent. Then,as shown in FIG. 27( f), the remained portion of the second metal wiringlayer 95 is used as a mask. By means of RIE, the first metal wiringlayer 93 formed under the second metal wiring layer 95 is remained, andan unnecessary portion of the first metal wiring layer 93 is removed,and the insulation film 92 formed thereunder is removed by using asolution of NH₄F, so as to form a fine T-gate electrode.

(6) The Sixth Application Example of the Present Invention: A Method forPreparing a Plasma Display

There is provided a method for preparing a plasma display as an exampleof applications of the resist pattern-improving material according tothe present invention for reducing the edge roughness. In the fifthapplication example described here, the resist pattern-improvingmaterial according to the present invention is applied to a positivetype resist pattern 104. See FIGS. 28 and 29.

With reference to FIG. 28 and FIG. 29, a process for forming a partitionwall in a plasma display is explained. FIGS. 28( a) to (d) and FIGS. 29(e) to (g) show cross-sectional views for illustrating processes forforming a partition wall. As shown in FIG. 28( a), an address electrode101 is formed on a glass base board 100. The glass base board 100 is,for example, made of a soda glass or high strain glass having athickness of 2.8 mm. After forming the address electrode 101, forexample, a surface preparation layer 102 of dielectric glass is formed.In the following explanations, the glass base board 100, addresselectrode 101, and surface preparation layer 102 may be referred to as abase board 103 for convenience. Then, as shown in FIG. 28( b), aphotosensitive coating layer 104 is formed on the base board 103. Thephotosensitive coating layer 104 is formed by using a positive typeresist material, to have a thickness of 120 nm. Then, as shown in FIG.28( c), an i ray is irradiated through a photo mask 105 having apredetermined width and pitch of the pattern. The amount of theirradiation is adjusted according to the width and pitch of the patternof the photo mask 105. As shown in FIG. 28( d), the irradiation isfollowed by development. A solution of sodium carbonate at a concentrateof 1% by mass is used for the development. The development is subjectedfor a period of about 3 minutes, followed by washing in water.Thereafter, as shown in FIG. 29( e), a plasma welding is carried out onthe base board 103, so as to deposit a welding film 107 of a partitionwall material at the inside of the grooved portions of thephotosensitive layer 104.

In detail, the plasma welding torch 108 is provided with a cooling gasport 110. Welding of the plasma jet 109 is concurrent with flowing ofthe cooling gas 111 toward the base board 103. Nitrogen gas is used asthe cooling gas 111. The cooling gas may reduce the damage of the photosensitive coating layer 104 due to heat under the welding, and thereby,a partition wall may be made finer. In the step of the welding, thewelding film 107 is generally deposited inside the grooves of thephotosensitive coating layer 104, in a manner to swell on the surface ofthe photosensitive layer 104. However, the photosensitive layer 104 isless deposed on the periphery thereof. Then, as shown in FIG. 29( f),the welding film 107 over the surface of the photosensitive coatinglayer 104 is generally removed by means of grinding, so as to flattenthe surface of the welding film 107 deposited inside the grooves of thephotosensitive coating layer 104. Then, as shown in FIG. 29( g), thebase board 103 is burned in an atmosphere including oxygen at a hightemperature, and thereby, the photosensitive resin of organic componentsis burned out and changed into gases, such as, carbon dioxide, forremoval. Thus, a partition wall 107 having a predetermined shape isformed on the base board 103. As described here, the partition wall fora plasma display is prepared. See FIG. 30.

The plasma display panel, as described here as an application example ofthe present invention, has a front base board 150 and a back base board151 opposed to the front base board 150. The front base board 150 isprovided with an indication electrode 152, 153, a dielectric layer 154,and an MgO dielectric protective layer 155 formed thereon in suchorders. The back base board 151 is provided with an address electrode156 and a dielectric layer 157 formed thereon, on which a partition wall158 is formed. The side surface of the partition wall 158 is coated witha fluorescence layer 159. Between the front base board 150 and the backbase board 151, an electric discharging gas 160 is filled at a specificpressure. The electric discharging gas 160 is discharged between theindication electrodes 152, 153 to generate an ultraviolet ray, whichirradiates the fluorescence layer 159 to make a picture indication, forexample, a color picture indication.

As described above, several application example of the present inventionare explained, based on preparation methods for various devices whichmay be applicable to the present invention. The resist pattern-improvingmaterial according to the present invention may reduce the edgeroughness in the step of patterning. It would be possible to continue touse photo irradiation techniques for a while, and to easily produce highdensity devices in mass production. This specification shows severalapplications, but the invention is not limited to the explanations here,and may be modified on the merit within the scope of the presentinvention.

For example, the above description says that the nonionic surfactant isselected from the group consisting of polyoxy ethylene-polyoxy propylenecopolymer, polyoxy alkylene alkyl ethers, polyoxy ethylene alkyl ethers,polyoxy ethylene derivatives, sorbic fatty acid esters, glycerin fattyacid esters, primary alcohol ethoxylates, and phenol ethoxylates.Alternatively, another surfactant not listed here may be selected solong as it is a nonionic surfactant. Such an alternative will accomplisha similar effect specific to the present invention.

Also, the above description says that the alicyclic type resistmaterials may include resist materials for ArF excimer laser, such asacrylic type resist materials having an adamantyl group on the sidechain. Alternatively, resist materials for ArF excimer laser, such as,acrylic type resist materials having a norbornene group on the sidechain, and the like, or resist materials for ArF excimer laser, such as,COMA (cycloolefin maleic acid anhydride type) type resist materials, andthe like, may be used. Also, a resist materials for ArF excimer laser,such as, alicyclic cycloolefins having an adamantyl group, norbornenegroup, and the like, on its main chain. Also, these resins listed heremay be fluorinated at a part of the main chain or side chain thereof,and if so, it will be possible to work in a fine manner since it makes aresist pattern applicable to irradiation of F₂ excimer laser light.

The explanations above relate to methods for various semiconductordevices, but the present invention may be applicable to the followings,which need small and fine patterns: for example, functional parts, suchas, mask pattern, rectil pattern, LCD (liquid crystalline display), SAWfilter (elastic surface wave filter), and so on; optical parts used forconnecting optical wiring; fine and small parts, such as, microactuators, and so on. Also, as an example application of semiconductordevices, a process for preparing a flash memory is explained in detail,but the present invention is not limited thereto. The present inventionmay be also applicable to a method for preparing a logic device, DRAM,FRAM, and so on.

Also, the applications described above is focused on explanations of theresist pattern-improving material according to the present invention,especially with respect to manufacturing processes and theirapplications. However, the explanation described above, such as, themixing ratio of the composition, must not limit the scope of theinvention.

According to the present invention, it is possible to form a goodpattern having a reduced edge roughness, resulting in maintaining a massproduction for preparing highly fine devices, without avoiding shortcircuit and bad condition patterns.

According to the present invention, several effects are expected. Forexample, it is possible to form a pattern which is controlled to haveless varied sizes. It is possible to use a laser exceeding anirradiation criticality of a deep ultraviolet irradiation, by using, forexample, an ArF (argon fluoride) excimer laser (having a wavelength of193 nm), and so on. Therefore, it may contribute to continue to usephoto irradiation working, and also, mass production for devices may becontained to use.

The symbols used in this specification are summarized below.

1: photo resist film, 1 a: resist pattern, 2: resist pattern-improvingfilm, 2 a: resist pattern having improved, 3: layer insulation film, 4:improved portion of the resist pattern, 22: Si base board (semiconductorbase board), 23, field oxidation film, 24 a: first gate insulating film,24 b: second gate insulating film, 25 a: first threshold controllinglayer, 25 b: second threshold controlling layer, 26, 27, 29, 32, 34, 43:resist film, 28, 28 a. first polysilicon film (first conductive film),28 b: gate electrode (first polysilicon film), 28 c: floating gateelectrode, 30 a, 30 c: capacitor insulating film, 30 b, 30 d. SiO₂film,31, 31 b: second polysilicon film (second conductive film), 31 a:control gate electrode, 33 a, 44 a: first gate portion, 33 b, 33 c, 44b: second gate portion, 35 a, 35 b, 36 a, 36 b, 45 a, 45 b, 46 a, 46:source drain region layer, 37, 47: layer insulation film, 38 a, 38 b, 39a, 39 b, 48 a, 48 b, 49 a, 49 b: contact hole, 40 a, 40 b, 41 a, 41 b,50 a, 50 b, 51 a, 51 b: source drain electrode, 42: high meltingtemperature metal film (fourth conductive film), 42 a: control gateelectrode (high melting temperature metal film, fourth conductive film),42 b: gate electrode (high melting temperature metal film, fourthconductive film), 52 a, 52 b: opening portion, 53 a, 53 b: high meltingtemperature metal film (third conductive film), 54: insulating film, 11:MR element portion, 12: terminal, 211: supporting material, 221: aluminalayer, 231: lower shield layer, 241: lower gap layer, 251: MR pattern,261: first resist layer, 271 monochromatic light, 291: second resistlayer, 301: i ray, 311: irradiation portion, 321: irradiation portion,331: terminal forming material, 411: MR element, 421, terminal, 431:first resist layer, 441: second resist layer, 61: supporting material,62, alumina layer, 63: lower shield layer, 63′: lower shield, 64: lowergap layer, 64′: lower gap, 65: MR film, 66: MR element, 67: maskpattern, 68: terminal, 81: metal film, 83: lower shield layer, 84: lowergap layer, 85: MR film, 85 a: MR element, 86: first resist layer, 87:second resist layer, 88: i ray, 89: two layer resist pattern, 90: GaAsbase board, 91: resist pattern, 92: insulating film, 92 a: openingportion, 93: first metal wiring layer, 94: resist layer, 94 a: openingportion, 95: second metal wiring layer, 100: glass base board, 101:address electrode, 102: surface preparation layer, 103: base board, 104:photosensitive resin layer, 105: photo mask, 107: welding film, 108:plasma welding torch, 109: plasma jet, 110: cooling gas port, 111:cooling gas, 150: front base board, 151: back base board, 152:indication electrode, 153: indication electrode, 154: dielectric layer,155: MgO dielectric layer protective layer, 156: address electrode, 157:dielectric layer, 158: partition wall, 159: fluorescence layer, 160:electric discharging gas, 300: layer insulation layer, 302: resistpattern, 304: opening portion, 306: plating surface preparation layer,308: thin film conductive layer(Cu plating film), 310: thin filmmagnetic coil, 312: non-magnetic base board, 314: gap layer, 316: resininsulating layer, 318: resist film, 318 a: resist pattern, 320: firstspiral pattern, 322: conductive surface preparation layer, 324: resistlayer, 326: resist pattern, 328: Cu conductive film, 330: thin filmmagnetic coil, 332: writable magnetic pole of a magnetic layer

1. A method for preparing a pattern, comprising: forming a resistpattern; and coating a resist pattern-improving material on the surfaceof the resist pattern, wherein the resist pattern-improving material ismixed with the resist pattern at the interface therebetween, wherein theresist pattern-improving material comprises: (a) a water-soluble oralkali-soluble composition, comprising: (i) a resin, and (ii) acrosslinking agent or nonionic surfactant, and (b) a water-solublearomatic compound, wherein the water-soluble aromatic compound isselected from the group consisting of polyhydric phenols represented bygallic acid, and derivatives thereof; naphthalene polyhydric alcoholsrepresented by naphthalenediol, naphthalenetriol, and derivativesthereof; and benzophenone derivative represented by alizarin yellow A,wherein the resist pattern is formed by irradiating an ArF excimar laserlight or a laser light having a wavelength shorter than that of the ArFexcimar laser light, and wherein the pattern of the resistpattern-improving material includes a base resin which does notsubstantially transmit the ArF excimar laser light.
 2. A method forpreparing a pattern according to claim 1, wherein the amount of theclosslinking is controlled by the coated film thickness, the temperaturefor baking, and/or the period for baking, to reduce the amount of theedge roughness of the resist pattern into a predetermined level.
 3. Amethod for preparing a pattern according to claim 2, wherein thevariation of the size of the resist pattern is controlled within therange of 10% and less, and wherein the amount of the edge roughness iscontrolled to reduce within the range of 5% and less, of the size of thepattern.
 4. A method for preparing a pattern according to claim 3,wherein a resist material is selected from the group consisting ofnovolac type, PHS type, acrylic type, COMA type, alicyclicacrylic hybridtype, and the fluorinated derivatives thereof.
 5. A method for preparinga pattern, comprising: forming a resist pattern; and coating a resistpattern-improving material on the surface of the resist pattern, whereinthe resist pattern-improving material, comprising: (a) a water-solubleor alkali-soluble composition, comprising: (i) a resin, and (ii) acrosslinking agent or nonionic surfactant, and (b) a water-solublearomatic compound, wherein the resist pattern-improving material ismixed with the resist pattern at the interface therebetween, wherein theamount of the mixing is controlled by the coated film thickness, thetemperature for baking, and/or the period for baking, to reduce theamount of the edge roughness of the resist pattern into a predeterminedlevel.
 6. A method for preparing a semiconductor device, comprising: (a)forming a resist pattern; (b) coating the resist pattern with a resistpattern-improving material to cover the surface of the resist pattern,thereby reducing an edge roughness of the resist pattern; and (c)patterning a surface preparation layer by means of dry etching whileusing the resist pattern having a reduced edge roughness as a mask, theresist pattern-improving material comprises: (a) a water-soluble oralkali-soluble composition, comprising: (i) a resin, and (ii) acrosslinking agent or nonionic surfactant, (b) a water-soluble aromaticcompound, and wherein the water-soluble aromatic compound is selectedfrom the group consisting of polyhydric phenols represented by gallicacid, and derivatives thereof; naphthalene polyhydric alcoholsrepresented by naphthalenediol, naphthalenetriol, and derivativesthereof; and benzophenone derivative represented by alizarin yellow A,wherein the resist pattern is formed by irradiating an ArF excimar laserlight or a laser light having a wavelength shorter than that of the ArFexcimar laser light, and wherein the pattern of the resistpattern-improving material includes a base resin which does notsubstantially transmit the ArF excimar laser light.
 7. A method forpreparing a pattern, comprising: (a) forming a resist pattern on asubstrate; (b) coating, on the resist pattern, a solution including atleast one surfactant selected from the group consisting of polyoxyethylene-polyoxy propylene copolymer, polyoxy alkylene alkyl ethers,polyoxy ethlene alkyl ethers, polyoxy ethylene derivatives, sorbic fattyacid esters, glycerin fatty acid esters, primary alcohol ethoxylates,and phenol ethoxylates; (c) coating a water-soluble or alkali-solublecomposition, comprising: (i) at least one resin selected from the groupconsisting of polyvinyl alcohol, polyvinyl acetal and polyvinyl acetate,(ii) at least one crosslinking agent selected from the group consistingof melamine derivatives, urea derivatives, and uril derivatives, and(iii) a water-soluble aromatic compound, and (d) baking the substrate tocause a crosslinking reaction, wherein the resist pattern is formed byirradiating an ArF excimar laser light or a laser light having awavelength shorter than that of the ArF excimar laser light, and whereinthe pattern of the resist pattern-improving material includes a baseresin which does not substantially transmit the ArF excimar laser light.8. A method for preparing a pattern according to claim 7, wherein inaddition to the base resin, the resist pattern-improving materialfurther includes at least one selected from the group consisting ofcrosslinking agents, water-soluble aromatic compounds, solvents,surfactants, thereby controlling the variation of the size of the resistpattern within the range of 10% and less.
 9. A method for preparing apattern, comprising: forming a resist pattern; and coating a resistpattern-improving material on the surface of the resist pattern, whereinthe resist pattern-improving material, comprising: (a) a water-solubleor alkali-soluble composition, comprising: (i) at least one resinselected from the group consisting of polyvinyl alcohol, polyvinylacetal and polyvinyl acetate, and (ii) at least one crosslinking agentselected from the group consisting of melamine derivatives, ureaderivatives, and uril derivatives, and (b) a water-soluble aromaticcompound, wherein the resist pattern-improving material is mixed withthe resist pattern at the interface therebetween, wherein the amount ofthe mixing is controlled by the coated film thickness, the temperaturefor baking, and/or the period for baking, to reduce the amount of theedge roughness of the resist pattern into a predetermined level.
 10. Amethod for preparing a pattern, comprising: forming a resist pattern;and coating a resist pattern-improving material on the surface of theresist pattern, wherein the resist pattern-improving material,comprising: (a) a water-soluble or alkali-soluble composition,comprising: (i) at least one resin selected from the group consisting ofpolyvinyl alcohol, polyvinyl acetal and polyvinyl acetate, and (ii) atleast one crosslinking agent selected from the group consisting ofmelamine derivatives, urea derivatives, and uril derivatives, and (b) awater-soluble aromatic compound selected from the group consisting ofpolyhydric phenols represented by resorcin, resorcin [4] arene,pyrogallol, gallic acid, and derivatives thereof; aromatic carboxylicacids represented by salicylic acid, phthalic acid, dihydroxybenzoicacid, and derivatives thereof; naphthalene polyhydric alcoholsrepresented by naphthalenediol, naphthalenetriol, and derivativesthereof; and benzophenone derivatives represented by alizarin yellow A,wherein the resist pattern-improving material is mixed with the resistpattern at the interface therebetween, wherein the amount of the mixingis controlled by the coated film thickness, the temperature for baking,and/or the period for baking, to reduce the amount of the edge roughnessof the resist pattern into a predetermined level.
 11. A method forpreparing a pattern, comprising: forming a resist pattern; and coating aresist pattern-improving material on the surface of the resist pattern,wherein the resist pattern-improving material is mixed with the resistpattern at the interface therebetween, wherein the resistpattern-improving material comprises: (a) a water-soluble oralkali-soluble composition, comprising: (i) at least one resin selectedfrom the group consisting of polyvinyl alcohol, polyvinyl acetal andpolyvinyl acetate, and (ii) at least one crosslinking agent selectedfrom the group consisting of melamine derivatives, and uril derivatives,and (b) a water-soluble aromatic compound, wherein the resist pattern isformed by irradiating an ArF excimar laser light or a laser light havinga wavelength shorter than that of the ArF excimar laser light, andwherein the pattern of the resist pattern-improving material includes abase resin which does not substantially transmit the ArF excimar laserlight.
 12. A method for preparing a pattern according to claim 11,wherein the variation of the size of the resist pattern is controlledwithin the range of 10% and less, and wherein the amount of the edgeroughness is controlled to reduce within the range of 5% and less, ofthe size of the pattern.
 13. A method for preparing a pattern accordingto claim 12, wherein a resist material is selected from the groupconsisting of novolac type, PHS type, acrylic type, COMA type,alicyclicacrylic hybrid type, and the fluorinated derivatives thereof.14. A method for preparing a pattern, comprising: forming a resistpattern; and coating a resist pattern-improving material on the surfaceof the resist pattern, wherein the resist pattern-improving material ismixed with the resist pattern at the interface therebetween, wherein theresist pattern-improving material comprises: (a) a water-soluble oralkali-soluble composition, comprising: (i) at least one resin selectedfrom the group consisting of polyvinyl alcohol, polyvinyl acetal andpolyvinyl acetate, and (ii) at least one crosslinking agent selectedfrom the group consisting of melamine derivatives, urea derivatives, anduril derivatives, (b) a water-soluble aromatic compound selected fromthe group consisting of polyhydric phenols represented by resorcin,resorcin [4] arene, pyrogallol, gallic acid, and derivatives thereof;naphthalene polyhydric alcohols represented by naphthalenediol,naphthalenetriol, and derivatives thereof; and benzophenone derivativesrepresented by alizarin yellow A wherein the resist pattern-improvingmaterial crosslinks by baking, wherein the resist pattern is formed byirradiating an ArF excimar laser light or a laser light having awavelength shorter than that of the ArF excimar laser light, and whereinthe pattern of the resist pattern-improving material includes a baseresin which does not substantially transmit the ArF excimar laser light.15. A method for preparing a pattern according to claim 14, wherein thevariation of the size of the resist pattern is controlled within therange of 10% and less, and wherein the amount of the edge roughness iscontrolled to reduce within the range of 5% and less, of the size of thepattern.
 16. A method for preparing a pattern according to claim 15,wherein a resist material is selected from the group consisting ofnovolac type, PHS type, acrylic type, COMA type, alicyclicacrylic hybridtype, and the fluorinated derivatives thereof.
 17. A method forpreparing a semiconductor device, comprising: (a) forming a resistpattern; (b) coating the resist pattern with a resist pattern-improvingmaterial to cover the surface of the resist pattern, thereby reducing anedge roughness of the resist pattern; and (c) patterning a surfacepreparation layer by means of dry etching while using the resist patternhaving a reduced edge roughness as a mask, the resist pattern-improvingmaterial comprises: (a) a water-soluble or alkali-soluble composition,comprising: (i) at least one resin selected from the group consisting ofpolyvinyl alcohol, polyvinyl acetal and polyvinyl acetate, and (ii) atleast one crosslinking agent selected from the group consisting ofmelamine derivatives, and uril derivatives, and (b) a water-solublearomatic compound, wherein the resist pattern is formed by irradiatingan ArF excimar laser light or a laser light having a wavelength shorterthan that of the ArF excimar laser light, and wherein the pattern of theresist pattern-improving material includes a base resin which does notsubstantially transmit the ArF excimar laser light.
 18. A method forpreparing a semiconductor device, comprising: (a) forming a resistpattern; (b) coating the resist pattern with a resist pattern-improvingmaterial to cover the surface of the resist pattern, thereby reducing anedge roughness of the resist pattern; and (c) patterning a surfacepreparation layer by means of dry etching while using the resist patternhaving a reduced edge roughness as a mask, the resist pattern-improvingmaterial comprises: (a) a water-soluble or alkali-soluble composition,comprising: (i) at least one resin selected from the group consisting ofpolyvinyl alcohol, polyvinyl acetal and polyvinyl acetate, and (ii) atleast one crosslinking agent selected from the group consisting ofmelamine derivatives, urea derivatives, and uril derivatives, (b) awater-soluble aromatic compound selected from the group consisting ofpolyhydric phenols represented by resorcin, resorcin [4] arene,pyrogallol, gallic acid, and derivatives thereof; naphthalene polyhydricalcohols represented by naphthalenediol, naphthalenetriol, andderivatives thereof; and benzophenone derivatives represented byalizarin yellow A, wherein the resist pattern-improving materialcrosslinks by baking wherein the resist pattern is formed by irradiatingan ArF excimar laser light or a laser light having a wavelength shorterthan that of the ArF excimar laser light, and wherein the pattern of theresist pattern-improving material includes a base resin which does notsubstantially transmit the ArF excimar laser light.